Answer:
the male gametophyte
Explanation:
Pollen grains are structures in the seed plants (spermatophytes) which contain vegetative cells but also reproductive cells - microgametophytes. Microgametophytes produce 2 male gametes or sperm cells. Vegetative cells produce pollen tube which is involved in the transfer of sperm cells to the ovule (female structure that forms female gametes). Pollen grains are different in shape, size and color, but all of them are enveloped with hard coat that has protective role.
Answer:
c is correct answer ......
DNA is negatively charged, therefore, when an electric current is applied to the gel, DNA will migrate towards the positively charged electrode.
Answer: B. Invasive species
An invasive species is a species of organisms which is introduced to a new ecosystem and increases in number rapidly. An invasive species complete with the native species for resources and the population of native species being weaker decreases in number, migrate to other locations or extinct. Here, foreign plants can be considered as invasive species because it limited the growth of native species and these foreign plants were only plants left after several growing seasons.
The correct answer is helper T cells.
<span>The helper T cells are one of the main cells of the adaptive immune system. Their role is to help the activity of other immune cells by releasing T cell cytokines and they are required for almost all adaptive immune responses. The helper T cells activate B cells to secrete antibodies, stimulate macrophages to destroy ingested pathogens, and help in activation of cytotoxic T cells to kill infected target cells.</span>
